If electrons have less mass than planck mass do they still exert gravitational force? What about atoms and other subatomic particles with mass?
We don't know of any reason why they shouldn't. But we don't know for sure, because the gravitational field produced by a Planck-mass object is too small to measure directly. The lightest object I know of whose gravitational field has been directly measured was 706 mg (http://jetp.ac.ru/cgi-bin/dn/e_067_10_1963.pdf), which is still 35,000 times the Planck mass.